To the average observer, it would seem that 44-year-old patient “SM” was just another typical mother of three: she scores normally on IQ tests, has good language skills and a decent memory. But, according to a paper by neurologists at the University of Iowa, SM is profoundly unusual. Because of a degenerative condition that left her with damage in certain brain structures, researchers say, SM is incapable of feeling fear.
The researchers know, because they spent several days trying to scare her silly. They exposed SM to snakes and spiders at a pet store, showed her clips of horror movies like The Shining and The Blair Witch Project, and took her through a haunted house in a former sanatorium. SM’s fear response? Nonexistent.
In fact, she relished cuddling snakes and had to be stopped from reaching for a tarantula.
SM has a genetic condition that has disabled, in both hemispheres, a brain region known as the amygdala, which is involved in processing emotional memories and fear. She has been studied by neurologists for 20 years because her case is so extreme, and has so far been shown to be unable to read social situations that involve fear or to recognize evidence of fear on the faces of others.